Powered hauling blocks are used on fishing vessels such as purse seiners for hauling nets from the water and depositing the nets on the deck of the vessel. The block includes a powered sheave that engages the net and forwards it through the block. To improve the grip the sheave can exert on the net, a variety of different cleats have been associated with the interior diverging net hauling surface of the sheave. The cleats have been made of a variety of materials and have taken a variety of shapes. Conventionally, cleats are formed of a hard rubber compound and positioned on the hauling surface of the sheave. The entire hauling surface as well as the cleat is then continuously coated with a rubber compound. When the cleats wear, the entire sheave must be stripped, new cleats laid down, and the sheave recoated. Another type of cleat is composed of a hard rubber compound that is bolted to the hauling surfaces. These cleats tend to deteriorate rather quickly and must be replaced quite often. Cleats have also been made of aluminum and are bolted or welded to the sheave. While they do offer satisfactory wear characteristics, the aluminum cleats are expensive and tend not to grip as well as rubber. Moreover, prior cleats have generally had parallel sides, which tend to cause the net to rise radially out of the bight of the sheave, which in turn tends to cause slippage of the net in the sheave.